Biaxial Piezoelectric MEMS Mirrors with Low Absorption Coating for 1550 nm Long-Range LIDAR.

This paper presents the fabrication and characterization of a biaxial MEMS (MicroElectroMechanical System) scanner based on PZT (Lead Zirconate Titanate) which incorporates a low-absorption dielectric multilayer coating, i.e., a Bragg reflector. These 2 mm square MEMS mirrors, developed on 8-inch silicon wafers using VLSI (Very Large Scale Integration) technology are intended for long-range (>100 m) LIDAR (LIght Detection And Ranging) applications using a 2 W (average power) pulsed laser at 1550 nm. For this laser power, the use of a standard metal reflector leads to damaging overheating. To solve this problem, we have developed and optimised a physical sputtering (PVD) Bragg reflector deposition process compatible with our sol-gel piezoelectric motor. Experimental absorption measurements, performed at 1550 nm and show up to 24 times lower incident power absorption than the best metallic reflective coating (Au). Furthermore, we validated that the characteristics of the PZT, as well as the performance of the Bragg mirrors in terms of optical scanning angles, were identical to those of the Au reflector. These results open up the possibility of increasing the laser power beyond 2W for LIDAR applications or other applications requiring high optical power. Finally, a packaged 2D scanner was integrated into a LIDAR system and three-dimensional point cloud images were obtained, demonstrating the scanning stability and operability of these 2D MEMS mirrors.

Antipsychotic drugs and the risk of recurrent venous thromboembolism: A prospective cohort study.

BACKGROUND: Numerous studies have suggested that antipsychotic drugs are associated with an increased risk for a first episode of venous thromboembolism (VTE). However, after anticoagulation discontinuation, the impact of antipsychotic drugs on the risk of recurrent VTE (rVTE) remains unknown. OBJECTIVE: To estimate the risk of rVTE in association with antipsychotic drugs. METHODS: Between May 2000 and December 2012, we included all consecutive patients with a first unprovoked symptomatic VTE and who discontinued anticoagulation. During follow-up, exposure to antipsychotic drugs was systematically assessed. RESULTS: A total of 736 patients with a first unprovoked symptomatic VTE were followed-up during a median period of 27.0 months (interquartile range (IQR) 6.2-60.0). Patients' median age was 66.0 years (IQR 49.0-76.0), 404 (54.9%) were men, and 61 (8.3%) were exposed to antipsychotics during follow-up. The incidence rate of r VTE was 12.1% person-year (95% CI 7.2-20.5) in antipsychotics users compared with 8.3% person-year (95% CI 7.1-9.8) in non-users (p = 0.20). Multivariate analysis showed a significant increased risk of recurrence associated with antipsychotic exposure (adjusted hazard ratio 1.9, 95% CI 1.1-3.3). CONCLUSIONS: In this cohort study, exposure to antipsychotic drugs was found to be associated with an increased risk of rVTE among patients with a previous first unprovoked symptomatic VTE and who discontinued anticoagulation. Larger studies are needed to confirm and further explore this association.

Low-loss submicrometer silicon-on-insulator rib waveguides and corner mirrors.

Rib microwaveguides are demonstrated on silicon-on-insulator substrates with Si film thickness of either 380 or 200 nm and a width of 1 microm. Corner mirrors that allow compact 90 degrees turns between two perpendicular waveguides are characterized. Measured propagation losses are approximately 0.4 dB/cm and approximately 0.5 dB/cm for 380-nm and 200-nm Si film, respectively, and mirror losses are approximately 1 dB. This allows the development of applications such as optical interconnects in integrated circuits over propagation distances larger than several centimeters.